Retrograde problems

[TAILLE]

#7, first attempt:

Spoiler:

21, 27, 37, 47, 48, 49 / 4, 11, 12, 14, 24, 33, 38, 39, 43; 1. 21-16 39-44 2. 16x18 38-42 3. 47x9 4x42

Congratualation Joost because such problem are not really easy!
Your score is 061000. By using your idea in the other direction you can reach the 060900 optimum score

Spoiler:

[ildjarn]

First idea for #6, not correct since there are several possibilities, but perhaps you can indicate whether I'm searching in the right direction? Or does 'you are not allowed to use kings' also apply to the solution?

Spoiler:

8, 39, 47, 48 / 11, 17, 22, 24, 25, 37, 38, 42; 1. 8-2 37-41 2. 2x49 22-27 3. 49x30 25x43.

[ildjarn]

Second idea for 6

Spoiler:

20 21 26 30 47 48 / 3 11 12 13 31 32 33 37 38
1. 21-16 37-41 2. 26×39 38-42 3. 16×9 3×43

[TAILLE]

First idea for #6, not correct since there are several possibilities, but perhaps you can indicate whether I'm searching in the right direction? Or does 'you are not allowed to use kings' also apply to the solution?

Spoiler:

8, 39, 47, 48 / 11, 17, 22, 24, 25, 37, 38, 42; 1. 8-2 37-41 2. 2x49 22-27 3. 49x30 25x43.

The best solution with kings is the following (score = 030602)

1...38-27 2.31x28 23x41
but effectively I asked four the ten diagrams to avoid using kings

[TAILLE]

Second idea for 6

Spoiler:

20 21 26 30 47 48 / 3 11 12 13 31 32 33 37 38
1. 21-16 37-41 2. 26×39 38-42 3. 16×9 3×43

Your score (061000) is almost optimum.
You can reach the 051000

Spoiler:

1...37-42 2.26x39 27-31 3.36x9 3x49

For your information, with 6 plies you can reach 060600

1.45-40 26-31 2.36x38 39-43 3.50x39 35x42

[ildjarn]

#9:

Spoiler:

25 32 40 43 44 45 / 8 9 14 16 17 20 29 30 34
1. 40-35 34-40 2. 45x23 14-19 3. 23x21 16x40

[TAILLE]

#9:

Spoiler:

25 32 40 43 44 45 / 8 9 14 16 17 20 29 30 34
1. 40-35 34-40 2. 45x23 14-19 3. 23x21 16x40

Very good Joost it is the optimum! Congratulations.

[ildjarn]

I finally found something for #8, but since it's 7 moves long I know it's not optimal.

Spoiler:

6, 9, 26, 28, 36, 47 / 11, 12, 17, 24, 25, 27, 34, 37, 41, 43, 44
1... 17-22 2. 28x8 27-31 3. 6x17 37-42 4. 47x20 25x21

[TAILLE]

I finally found something for #8, but since it's 7 moves long I know it's not optimal.

Spoiler:

6, 9, 26, 28, 36, 47 / 11, 12, 17, 24, 25, 27, 34, 37, 41, 43, 44
1... 17-22 2. 28x8 27-31 3. 6x17 37-42 4. 47x20 25x21

Very good start, you are not very far from the optimum (060900).

Instead of starting from the position


try the following one

[ildjarn]

Spoiler:

8, 9, 26, 36, 42, 47 / 22, 24, 25, 27, 32, 33, 38, 41
1. 42-37 27-31 2. 37x17 38-42 3. 47x20 25x21

[TAILLE]

Spoiler:

8, 9, 26, 36, 42, 47 / 22, 24, 25, 27, 32, 33, 38, 41
1. 42-37 27-31 2. 37x17 38-42 3. 47x20 25x21

Yes Joost it is THE solution
Congratulations

[ildjarn]

That only leaves #10, but I doubt I can solve that one.

[TAILLE]

That only leaves #10, but I doubt I can solve that one.

Yes Joost the #10 problem is very difficult if you are not allowed to use kings.

By the way and with more experience I change the way to calculate the score because I do not like to calculate the number of kings and get a negative number and in addition it does not give a good indication of the dfficulty of the problem.
Instead of comparing the intial and the final position I am now convinced that it is far better to consider only the pieces captured.

My new proposal for calculating the score is the following:

pliesNumber = total number of plies
piecesAddedNumber = total number of pieces captured
kingsAddedNumber = total number of kings captured
score = (10000 * pliesNumber) + (100 * piecesAddedNumber) + kingsAddedNumber

To come back to #10 problem you can try to solve it with kings allowed. Yhe optimal score is 03 06 02

Solution of #10 problem when kings are not allowed

Spoiler:

20-14 33-39 44x42 34-39 49x9 4x13 35x33 13-18 14x21 16x20

[ildjarn]

Yes, with kings it's easy, 24-13 9×23 28×10

[TAILLE]

Hi Joost,

I would like to show you a very exceptionnal position



Though it is not easy you can try to find the solution with the best score which is 070702.

What is exceptionnal in this position is the solution if you are not allowed to use kings. In this hypothesis the problem is absolutely terrific. Do not take to much time on it because it is out of the scope of humans. I will show you the solution in my next post in order for you to first appreciate the difficulty.